Re: Help with HALLab telemetry
Re: Help with HALLab telemetry
- Subject: Re: Help with HALLab telemetry
- From: Jeff Moore <email@hidden>
- Date: Thu, 23 Sep 2010 11:25:10 -0700
The IO cycle duration for this set up (2055 frames at 176.4k) is about 11.6 milliseconds. The telemetry shows that the cycle entered the write kernel trap within 1ms of it starting to run. There doesn't seem to be anything wrong with that.
The kIOReturnOverrun is returned from the driver's processing in the kernel trap. Flipping through the code, it looks like this error is only going to be returned when the driver thinks something has gone off the rails, but only in the non-mixable case. It's hard to tell from the circumstances exactly which branch of the code is producing the error.
Probably the best thing to do is to file a bug so that the driver team can take a look at it.
--
Jeff Moore
Core Audio
Apple
On Sep 23, 2010, at 8:37 AM, Stephen F. Booth wrote:
> I'm debugging a strange issue with my audio player and I'm not sure how to interpret the HALLab telemetry results. The problem I'm having is that as soon as I start the device I immediately receive continuous overload notifications. So far the problem seems to only occur when my player is launched with the device sample set to 176.4 or 192.0; at 96.0 and below everything works as expected. I should also probably mention that for FW devices everything appears to work OK; I'm only seeing the problem with USB devices. The final piece of strangeness is that the problem only happens when I perform IO in a non-mixable format; if I stick with floats playback is fine.
>
> Here is a representative screenshot of the HALLab telemetry:
> http://img838.imageshack.us/img838/6475/screenshot20100923at822.png
>
> I notice the <-Write error 0xE00002E8. I'm not certain what this error indicates; does this mean the device is returning a kIOReturnOverrun error? What do these telemetry data indicate?
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